Contact Bernie Klocko at Bjkaboom@aol.com
He is a gunsmith and Vice Pres. of the 1000 yard club we shoot at in Williamsport, PA
He works with a lot of those actions on custom guns. When he buys a full rifle the first thnk he does is to put a new correct twist barrel on for the heavier bullets, a new stock and he also barrel blocks the outfit into the new stock at times.
Last year he mentioned some of the problems you are experiancing. He said he can't seem to get the accuracy out of them the way they come from the factory because he also likes the heavier match bullets with a high BC. The factory twist is wrong for them.